The morning-show host is recovering from MDS, a blood and bone marrow disease. She looked thin with close-cropped hair but was smiling broadly, back at work on "Good Morning America" at ABC's studio in New York City.

Roberts was welcomed back in a taped message from President Barack Obama and his wife, Michelle, former ESPN colleagues and Magic Johnson.

ABC announced Roberts will interview the first lady later this week, to be shown next Tuesday.

ABC News President Ben Sherwood came into the studio to give fist bumps to the anchors at the 7:25 a.m. break. He said Roberts' health will be closely monitored to make sure she doesn't overdo it at the beginning.

"This was up to Robin, her doctors and God," Sherwood said. "It's a day that we all rejoice."

ABC didn't miss a beat with her absence, continuing in first place in the ratings after first overcoming NBC's "Today" show last spring. Sherwood said the success with Roberts' absence surprised him.